1. Field of the Invention
The present invention relates to a fluid pressure-responsive unit that can be used, for example, on a fluid closed circuit wherein fluid can be subjected to expansion or compression.
2. Description of the Prior Art
A prior art search made by the present applicant has revealed U.S. Pat. No. 4,833,973 of May 30, 1989 to WANG, which patent relates to a fluid pressure-actuated assembly including a resilient cup-shaped housing made of rubber, of which the open end has a radial outer flange fluid-tightly fixed to a base plate having a conduit for leading a fluid in and out of the housing. A spring assembly surrounds the housing and allows it to expand against its bias when the fluid pressure increases, and allows it to return to retracted position when the pressure is reduced. As an example, the assembly is used in conjunction with the hydraulic circuit of a height-adjustable chair. The housing has a single conduit through which the oil flows in and out depending on whether the oil pressure increases or decreases. One drawback with the present assembly resides in the fact that no overflow means is provided for eliminating gas from the chamber when the fluid used is a liquid. Also, the rubber casing is not appropriate with any fluid, because its characteristics deteriorate with time in contact with certain fluids.
The following other patents found during the search have revealed the following US patents which are considered of little pertinency with respect to the present invention:
U.S. Pat. No. 1,886,803, J. V. GIESLER, 1932 PA1 U.S. Pat. No. 1,928,368, G. E. COFFEY, 1933 PA1 U.S. Pat. No. 3,211,184, E. M. GREER, 1965 PA1 U.S. Pat. No. 3,295,458, A. P. G. STEFFES, 1967 PA1 U.S. Pat. No. 3,485,258, G. B. GREENE, 1969 PA1 a base plate and a top plate; PA1 a bellows sidewall made of heat-exchange material and fluid tightly connected, at its ends, respectively to said base and top plates, said bellows sidewall defining, with said plates, a fluid chamber; PA1 resilient return means interconnecting said plates for allowing them to move relative to one another, whereby said chamber may expand and contract responsive to fluid pressure fluctuations; PA1 a fluid intake aperture formed in said base plate for admitting fluid into said chamber; PA1 a fluid overflow conduit in said chamber, said conduit having a first end provided with a connecting means for fixing said first end inside said chamber, said first end being fixed in a predetermined position for receiving fluid overflowing from said chamber, and a second end provided with a connecting means by which said second end can be connected to another conduit introduced into said chamber by means of said fluid intake aperture for leading overflowing fluid out of said chamber; and PA1 guiding and stopping means interconnecting said plates for guiding them when they move relative to one another, and for limiting expansion of said chamber when the distance between said plates reaches a predetermined length.
Also, one drawback with the expansion chambers known in the art reside in the fact that they are subjected to leaking.
An object of the present invention is to provide a fluid pressure-responsive unit that prevents the leaking of fluids and that can be used for cooling the fluid.